How do you report someone for boosting?

I found someone who is boosting someone's account. Literally you see them have tons of negative games as an adc and a couple negative games as jungler with some wins and some losses. and then all of a sudden lots of wins with 17-1 18-0 20-3. Someone is boosting the account and I want to know how to report that.

Is it possible to send in a ticket to them? Like what do I need to do to bring this to Riot's attention because that isn't fair to the people in my elo and it isn't fair that some terrible player is paying money just because he sucks at the game to make sure he gets the benefit of the skin.